Drill bits for boring into rock to install roof bolts in underground mines and the like, have a hardened tungsten carbide blade mounted in a slot at the distal end of a tubular bit body. The bit body has access ports that communicate with the inner bore and a vacuum is drawn through the hollow bore of the drill bit to remove fines cut by the drill. In an alternate configuration, pressurized water may be forced through the inner bore of a hollow drill bit and out the ports near the blade to cool the blade and remove dust during the cutting process.
The roof drilling machines that force such drill bits into the ceilings of mines use hydraulics to apply great force to the lower end of the bit to force the cutting end into the hard rock and other strata. Where the cutting end of the drill bit is configured to maximize the drilling rate, the forces applied to the cutting edge of the blade are also maximized, which in turn can contribute to the failure of the blade.
Another problem with existing drill bits is that the cutting blade thereof may remove chunks of rocks that may be relatively large compared to the diameters of the passageways through which those chips must move as they are drawn away from the blade. It would be desirable therefore, to provide an improved drill bit and blade which when subjected to the strong forces of a drilling machine, would have a reduced penetration rate to thereby reduce the forces on the blade such that the overall life of the drill bit and blade are extended. It would also be desirable to provide a drill bit and blade that would assist in the fragmenting of chunks of strata broken loose near the center of the blade to improve the removal thereof.